A variety of medical procedures utilize a laser or other radiation source to irradiate a tissue target. Examples of such procedures include dermatological therapies such as treatment of vascular lesions and removal of tattoos and unwanted hair, as well as non-dermatological procedures such as photodynamic therapy (PDT) for treatment of tumors. In procedures involving irradiation of a tissue target, it is usually desirable to match the spectral characteristics of the light produced by the radiation source with the absorption characteristics of the target. This matching promotes efficient absorption of the radiation by the target (which is necessary to effect the localized heating or ablation of the target) and may minimize thermal damage to adjacent tissue.
To facilitate matching of the spectral characteristics of the radiation source with the absorption characteristics of the target, some medical procedures employ a dye laser as the radiation source. An example of one such dye laser is described in U.S. Pat. No. 5,066,293 to Furomoto (“Light Amplifier and Method of Photothermolysis”). The output wavelength of the dye laser is controlled by means of the choice of dye and/or adjustment of a tuning element such as an intracavity rotatable birefringent filter. Further, dye lasers are typically capable of delivering radiation having output energies and pulse durations suitable for a range of medical applications.
Disadvantages associated with dye lasers include their high expense and complexity. Misalignment of or damage to optical components, malfunctioning of the dye recirculation system, and/or problems with control circuitry may cause the tunable dye laser to become partially or fully inoperative, leading to downtime and substantial repair or replacement costs. Further, owing to their relative complexity, it may be necessary to provide extensive training and practice to clinicians before they are able to competently operate dye laser-based systems.